Magnetically actuated switching contact set



1966 H. ANGERMAIER 3,

MAGNETICALLY ACTUATED SWITCHING CONTACT SET Filed July 25. 1965 United States Patent 3,288,972 MAGNETKCALLY ACTUATED SWITCHING CUNTACT SET Hugo Angermaier, Munich, Germany, assignor to Siemens & Halslre- Alrtiengesellschaft, Munich, Germany Filed July 23, 1965, Ser. No. 474,325 Claims priority, application Germany, Aug. 13, 1964, S 92,626 12 Claims. (Cl. 200-466) This invention concerns a switching contact set which has fiat magneti zable spring contacts, at least in the switching area, which contacts also serve as electrical conductors. Such contacts are used in particular for sealed contact, or dry reed contact switches.

In switching contacts of this kind, the spring contacts conduct the effective magnetic flux, as well as serve as electrical conductors. For this reason, it is advantageous to provide two separate conducting paths, one for the magnetic flux and the other for the electrical current, in order that the one path for magnetic flux may be designed of optimum properties for that purpose, and the other path for electrical current may be similarly designed of optimum properties for that purpose. Furthermore, it is desirable that the contact pressure upon actuation remain such as to hold the contacts together afiirmatively and fixedly until just before interruption of contact engagement, in order to avoid pitting of the contacts, and other adverse effects consequent of varying contact pressure, and the like.

It has been suggested in the past that one of the two spring contacts with engage together, could be supplied with an additional spring which would cooperate with a switching armature or stop fixed to the opposed spring contact, to form the switching contacts, while the fluxconducting path is established through the spring contacts themselves. One serious disadvantage of this suggestion, however, is the fact that additional components are thereby required, and must be attached to the spring contacts, and that a new set of tolerances is provided in the construction, which themselves must be eliminated or compensated for by adjustments, so that the manufacture of the switching contact set is considerably more expensive. On the other hand, the life span of such suggested switching contact sets is also reduced, since the points of attachment of the additional spring and the switching armature are themselves adversely affected by repeated switching actions. Finally, the space taken up by the switching contact set is necessarily increased when the additional spring and armature are added.

In comparison to this prior suggestion, the present invention has for its object the furnishing of a switching contact set which is simple in manufacture, and therefore less expensive, and which also takes up less space and has a longer dependable life span.

This and other objects of the invention is achieved, not by furnishing additional elements so that the two functions can be separately performed, but rather by constructing at least one of the spring contacts in such manner as to achieve that purpose. More particularly, at least one of the spring contacts is provided with one or more slots to furnish at least a pair of tongues of different widths, one of the tongues being arranged to come into direct contact with the opposed spring contact upon actuation, but the narrower tongue having thereupon a layer of contact material which extends above the plane defined by the flat surface of the other tongue. In this arrangement two separate paths are provided for the magnetic flux and the electrical current, the path for the electrical current including the tongue provided with the contact material, which obviously can be of optimum characteristics for that purpose. The other tongue, therefore, need only be ICC designed for magnetic flux conduction purposes and may be selected and manufactured to have optimum characteristics for that purpose.

A further advantage of the construction of the present invention over that of the prior art, employing separate elements for the two different functions, is that a portion of the magnetic flux in the apparatus of the invention flows through the tongues of the spring contacts which serve to conduct electrical current. Therefore, more of the space which is taken up by the elements of the switching set is used to conduct magnetic flux, and the size of the apparatus may accordingly be decreased, even though the same magnetic attractive force can be achieved. This, of course, is in addition to the reduction of size attendant the elimination of the need for additional springs and other parts, which are necessary in known arrangements provided for the purpose of the invention.

A further advantage of the construction of the invention is that the magnetic holding force required to be supplied to maintain the actuated contacts in engagement is kept at a minimum, since the broad tongues of the apparatus of the invention, in direct contact without an air gap, provide a high magnetic permeance.

A further advantage of the present invention arises out of the fact that there is only one variation, which gives rise to tolerances in the construction and operation of the switching apparatus, namely, the thickness of the contact layer. This is in contrast to the prior art solutions to the problems, by which a number of variations or tolerances in characteristics were to be expected. The result of the invention is that the operating characteristics of the switching contacts may be confined to a very narrow tolerance range, during manufacture thereof.

A further advantage of the switching contact set of the invention is that a satisfactory contact pressure is maintained at all times from contact actuation up until just before interruption of the actuated contacts. This relationship occurs by reason of the added thickness of the tongue or tongues carrying the electrical contact layer, as compared with the tongue carrying the magnetic flux, primarily. By reason of this relationship, good contact engagement occurs even when the magnetic holding force between the parts of the spring contacts which directly engage each other is reduced to the level of the initial spring tension. Moreover, when, through the continued reduction of the magnetic holding force, the parts which are directly engaged (and primarily carry the magnetic flux) disengage, the parts primarily carrying the electrical current disengage very abruptly, since the initial spring tension of the parts in direct engagement is greater, by reason of their greater width.

A final advantage of the apparatus of the invention is that the life span and operational safety are quite high, since the spring contacts are simple parts being provided only with slots, and failure through wear and tear of spot-welded or otherwise afiixed additional components, as would occur in the known systems, does not happen.

As will be apparent from the detailed description in conjunction with the forms of the invention shown in the drawings, the layer of contact material ,provided for the engagement between the narrower contact tongues, can be provided upon either of the spring contact members, or upon both of such members. Such layer can be plated onto the spring contact, as well as being evaporated on that contact, or the contact layer can be provided through galvanization.

The spring contacts may also be slotted in such fashion as to each have two tongues of different widths, with the tongues of the same width in engagement with each other upon actuation of the contact set. In an alternative form, the different width tongues may be at opposite sides of the center line of the contact set, so that the small electrical contact tongues engage the large tongues of the opposite spring contacts. In this latter arrangement, not only are the two spring contacts constructed in like fashion, but also a symmetrical division of the magnetic flux is guaranteed, so that a canting or tilting of the tongues is avoided and a satisfactory operation of the switching contacts is also guaranteed.

A further embodiment of the invention employs switching contacts having two longitudinal slots therein such as to form three tongues, which are preferably symmetrically distributed along the width of the spring contact. In such case, either the center tongue or the two outer tongues may come into direct engagement with the opposite spring contact, without the intervening electrical contact material. In both of these forms a double switching contact is of course developed, the advantages of such design being well known.

The invention will now be more fully described in conjunction with operative embodiments thereof shown in the accompanying drawing.

In the drawing:

FIG. 1 is a partial perspective view of a pair of switching contacts constructed in accordance with the invention;

FIGS. 2 and 3 are simplified diagrammatic views of the opposite surfaces of the switching contacts of FIG. 1, with FIG. 2 showing the contacts in rest position, and FIG. 3 showing them in engagement;

FIGS. 4 and 5 are views similar to FIGS. 2 and 3, showing the respective rest and engagement positions of a modified form of the contact set of FIG. 1;

FIG. 6 is a view similar to FIG. 4 of a further modified version of the apparatus of the invention;

FIGS. 7 and 8 are views similar to FIGS. 2 and 3 showing a further modified form of the invention in which both contact members are provided with longitudinal slots;

FIGS. 9 and 10 are views respectively similar to FIGS. 2 and 3 showing the electrical contact element as including the center tongue of one of the switch contacts;

FIG. 11 shows the rest position of a double-throw form of the switching contact set of the invention;

FIGS. 12 and 13 illustrate the use of only a single slot in the apparatus of the invention; and

FIGS. 14 and 15 illustrate the use of a single slot on each contact element, but with the electrical contact members at opposite sides of the center line of the apparatus.

FIG. 1 shows two flat spring contacts of magnetizable material, 1 and 2, of the type which would be utilized in sealed contact sets of the kind termed dry reed contacts. The two spring contacts overlap, with their free ends forming an air gap 3 between the parts thereof which are to engage.

The spring contact 1 is provided, in accordance with the invention, with two slots 4 and 5, so that three longitudinal tongues la-lc are provided at the end of the spring contact 1. It will be noted that the center tongue 1b is wider than either of the outer tongues, and indeed the width is preferably such that it exceeds the sum of the widths of the outer tongues. The outer contact tongues 1a and 1c are shown as provided with a special contact material 6 and 7 which extends upwardly from the plane defined by the flat upper surface of the contact member 1. These contact surfaces or layers 6 and 7 are preferably of material chosen for their good characteristics for electrical switching and may be plated onto the element 1.

FIGS. 2 and 3 contrast the unactuated or rest position and the operating position of the contact set, with FIG. 3 showing the spring contacts in engagement with each other to eliminate the air gap 3. It will be seen from these figures that the magnetic flux path includes the central tongue 1b and the contact member 2, while the electrical path includes the tongues 1a and 1c, the contact material layers 6 and 7 and the contact element 2. It

should be evident also from examination of FIG. 3 that the tongues 1a and 1c are pressed toward tongue 2 with a greater force than that urging tongue 1b into contact with the spring contact 2, this being by reason of the intervening contact layers 6 and 7 which prevent the tongues Ia and 112 from coming into direct engagement with the spring contact 2. As a result, the contact pressure of the electrical circuit is determined by the thickness of the contact layers, as well as by the spring characteristics of the tongues themselves.

The spring contact sets shown in FIGS. 415 are different design examples of the invention and are distinguished from each other and from those of FIGS. 1-3, only through dilferent arrangement of slots and positions of layers of contact material. Accordingly, similar parts in the various figures are provided with corresponding reference designations.

Referring first to the construction of FIGS. 4 and 5, it will be seen that the spring contact 2 is also provided with plating material, in this construction. In contrast, in FIG. 6 only the contact element 2 is provided with plating material, the spring contact element 1 not having such material.

In the construction of FIGS. 7 and 8, it will be seen that both the spring contact elements 1 and 2 have the same tongue arrangement at their ends, as well as having the same contact layers.

In the embodiment of FIG. 9, the center tongue is used as the electrical current-conducting tongue, while the outer tongues are the magnetic contact elements. That is, the center tongue is provided with the contact layer, while the outer tongues function primarily to conduct magnetic flux.

It will of course be evident that the embodiment of FIGS. 9 and 10 could further be modified so that the spring element 2 was slotted, in similar fashion to the spring element 1.

The embodiment of FIG. 11 illustrates the use of the invention in connection with a double-throw type of switch. In that embodiment, the center member 12 is not slotted but does carry center electrical contact layers. The two outer contact members 8 and 9 are both similarly slotted to form three tongues, with the center tongues provided with electrical contact material. FIG. 11 shows the apparatus in the rest position.

The embodiment of FIGS. 12 and 13 employs only a single slot 5, so that the contact element 1 only has a single tongue which carries the electrical contact material. In contrast, the embodiment of FIGS. 14 and 15 has each contact element I and 2 provided with a single slot, but with the slots arranged at opposite sides of the center line of the contact set, so that the electrical contact tongue of the element 1 engages the large contact portion of the element 2, While the electrical contact material on the contact tongue of the switch contact 2 also engages the large non-plated tongue of the contact 1.

It will be evident that many other changes could be made to form various additional embodiments of the invention. Accordingly, the invention is not to be considered limited to the embodiments specifically described herein, but rather only by the scope of the appended claims.

Iclaim:

1. In a sealed electrical contact set including a pair of spring contacts of magnetic material having end portions opposite each other which engage upon switch actuation and which must carry both magnetic flux and electrical current, the improvement comprising:

at least one of said spring contacts having at least a pair of longitudinally-extending tongues at said end portion defined by at least one slot extending inwardly of the contact from the end thereof, said tongues being of unequal width,

and at least one electrical contact layer on one of the spring contacts in position such as to be between the narrower of said tongues and the opposite contact, so that the wider tongue may be directly engaged with the other contact when the switch is actuated.

2. The apparatus of claim 1 in which said electrical contact layer is at least on said narrower tongue.

3. The apparatus of claim 2 including a second electrical contact layer on the other contact in position to be engaged by said first-mentioned layer upon switch actuation.

4. The apparatus of claim 1 in which said electrical contact layer is on the contact opposite the said narrower tongue.

5. The apparatus of claim 1 in which both of said contacts have at least a pair of longitudinally-extending tongues at the respective said end portions defined by at least one slot extending inwardly of the contact from the end thereof, the tongues on each contact being of unequal width, each of said narrower tongues carrying an electrical contact layer.

6. The apparatus of claim 5 in which said narrower tongues are opposite each other so that the two contact layers engage upon switch actuation.

7. The apparatus of claim 5 in which said narrower tongues are at opposite sides of the contact set from each other so that the contact layer on each narrow tongue directly engages the wider tongue of the other contact.

8. The apparatus of claim 1 in which at least said one contact has three said tongues defined by a pair of parallel said slots, with two of said three tongues being of equal width but of total width less than the third tongue, there being two electrical contact layers on at least one of the spring contacts in position such as to be between said two tongues and the opposite contact, so that the third tongue may be directly engaged with the other contact when the switch is actuated.

9. The apparatus of claim 8 in which there are electrical contact layers on both said contacts, with the contact layers on different contacts opposite each other so as to engage each other when the switch is actuated.

10. The apparatus of claim 8 in which said third tongue is between the other two tongues.

11. The apparatus of claim 1 in which at least said one contact has three said tongues defined by a pair of parallel said slots, with the contact layer between the narrowest tongue and the opposite contact, the width of each of the other tongues being greater than that of said narrowest tongue.

12. The apparatus of claim 11 in which said narrowest tongue is between the other two tongues which are of equal width.

References Cited by the Examiner UNITED STATES PATENTS 3,188,426 6/1965 Wessel 200-87 ROBERT K. SCHAEFER, Primary Examiner. 

1. IN A SEALED ELECTRICAL CONTACT SET INCLUDING A PAIR OF SPRING CONTACTS OF MAGNETIC MATERIAL HAVING END PORTIONS OPPOSITE EACH OTHER WHICH ENGAGE UPON SWITCH ACTUATION AND WHICH MUST CARRY BOTH MAGNETIC FLUX AND ELECTRICAL CURRENT, THE IMPROVEMENT COMPRISING: AT LEAST ONE OF SAID SPRING CONTACTS HAVING AT LEAST A PAIR OF LONGITUDINALLY-EXTENDING TONGUES AT SAID END PORTION DEFINED BY AT LEAST ONE SLOT EXTENDING INWARDLY OF THE CONTACT FROM THE END THEREOF, SAID TONGUES BEING OF UNEQUAL WIDTH, AND AT LEAST ONE ELECTRICAL CONTACT LAYER ON ONE OF THE SPRING CONTACTS IN POSITION SUCH AS TO BE BETWEEN THE NARROWER OF SAID TONGUES AND THE OPPOSITE CONTACT, SO THAT THE WIDER TONGUE MAY BE DIRECTLY ENGAGED WITH THE OTHER CONTACT WHEN THE SWITCH IS ACTUATED. 